Compositionality, Decompositionality and Refinement in Input/Output Conformance Testing - Technical Report
This work addresses conformance testing for component-based systems, offering incremental improvements by extending existing theories with modal refinement and decompositionality.
The paper tackles the problem of input/output conformance testing by proposing a theory based on Modal Interface Automata with Input Refusals (IR-MIA), which supports positive and negative testing with optimistic and pessimistic assumptions. It shows that the resulting modal-irioco relation is compositional, preserved under refinement, and facilitates decompositionality for component-based systems.
We propose an input/output conformance testing theory utilizing Modal Interface Automata with Input Refusals (IR-MIA) as novel behavioral formalism for both the specification and the implementation under test. A modal refinement relation on IR-MIA allows distinguishing between obligatory and allowed output behaviors, as well as between implicitly underspecified and explicitly forbidden input behaviors. The theory therefore supports positive and negative conformance testing with optimistic and pessimistic environmental assumptions. We further show that the resulting conformance relation on IR-MIA, called modal-irioco, enjoys many desirable properties concerning component-based behaviors. First, modal-irioco is preserved under modal refinement and constitutes a preorder under certain restrictions which can be ensured by a canonical input completion for IR-MIA. Second, under the same restrictions, modal-irioco is compositional with respect to parallel composition of IR-MIA with multi-cast and hiding. Finally, the quotient operator on IR-MIA, as the inverse to parallel composition, facilitates decompositionality in conformance testing to solve the unknown-component problem.